|
| 1 | +/*------------------------------------------------------------------------- |
| 2 | + * |
| 3 | + * repeater.c |
| 4 | + * Simple demo for remote plan execution patch. |
| 5 | + * |
| 6 | + * Transfer query plan to a remote instance and wait for result. |
| 7 | + * Remote instance parameters (host, port) defines by GUCs. |
| 8 | + * |
| 9 | + * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group |
| 10 | + * Portions Copyright (c) 2018-2019, Postgres Professional |
| 11 | + *------------------------------------------------------------------------- |
| 12 | + */ |
| 13 | + |
| 14 | +#include "postgres.h" |
| 15 | + |
| 16 | +#include "access/xact.h" |
| 17 | +#include "commands/extension.h" |
| 18 | +#include "executor/executor.h" |
| 19 | +#include "fmgr.h" |
| 20 | +#include "libpq/libpq.h" |
| 21 | +#include "libpq-fe.h" |
| 22 | +#include "optimizer/planner.h" |
| 23 | +#include "tcop/utility.h" |
| 24 | +#include "utils/guc.h" |
| 25 | + |
| 26 | +PG_MODULE_MAGIC; |
| 27 | + |
| 28 | +void _PG_init(void); |
| 29 | + |
| 30 | +static ProcessUtility_hook_type next_ProcessUtility_hook = NULL; |
| 31 | +static ExecutorStart_hook_type prev_ExecutorStart = NULL; |
| 32 | +static ExecutorEnd_hook_type prev_ExecutorEnd = NULL; |
| 33 | + |
| 34 | +static void HOOK_Utility_injection(PlannedStmt *pstmt, const char *queryString, |
| 35 | + ProcessUtilityContext context, ParamListInfo params, |
| 36 | + QueryEnvironment *queryEnv, DestReceiver *dest, |
| 37 | + char *completionTag); |
| 38 | +static void HOOK_ExecStart_injection(QueryDesc *queryDesc, int eflags); |
| 39 | +static void HOOK_ExecEnd_injection(QueryDesc *queryDesc); |
| 40 | + |
| 41 | +/* Remote instance parameters. */ |
| 42 | +char *remote_server_fdwname; |
| 43 | + |
| 44 | +static bool ExtensionIsActivated = false; |
| 45 | +static PGconn *conn = NULL; |
| 46 | + |
| 47 | +/* |
| 48 | + * Module load/unload callback |
| 49 | + */ |
| 50 | +void |
| 51 | +_PG_init(void) |
| 52 | +{ |
| 53 | + DefineCustomStringVariable("repeater.fdwname", |
| 54 | + "Remote host fdw name", |
| 55 | + NULL, |
| 56 | + &remote_server_fdwname, |
| 57 | + "remoteserv", |
| 58 | + PGC_SIGHUP, |
| 59 | + GUC_NOT_IN_SAMPLE, |
| 60 | + NULL, |
| 61 | + NULL, |
| 62 | + NULL); |
| 63 | + |
| 64 | + /* ProcessUtility hook */ |
| 65 | + next_ProcessUtility_hook = ProcessUtility_hook; |
| 66 | + ProcessUtility_hook = HOOK_Utility_injection; |
| 67 | + |
| 68 | + prev_ExecutorStart = ExecutorStart_hook; |
| 69 | + ExecutorStart_hook = HOOK_ExecStart_injection; |
| 70 | + |
| 71 | + prev_ExecutorEnd = ExecutorEnd_hook; |
| 72 | + ExecutorEnd_hook = HOOK_ExecEnd_injection; |
| 73 | +} |
| 74 | + |
| 75 | +static bool |
| 76 | +ExtensionIsActive(void) |
| 77 | +{ |
| 78 | + if (ExtensionIsActivated) |
| 79 | + return true; |
| 80 | + |
| 81 | + if ( |
| 82 | + !IsTransactionState() || |
| 83 | + !OidIsValid(get_extension_oid("repeater", true)) |
| 84 | + ) |
| 85 | + return false; |
| 86 | + |
| 87 | + ExtensionIsActivated = true; |
| 88 | + return ExtensionIsActivated; |
| 89 | +} |
| 90 | + |
| 91 | +#include "miscadmin.h" |
| 92 | +#include "pgstat.h" |
| 93 | +#include "storage/latch.h" |
| 94 | + |
| 95 | +#include "foreign/foreign.h" |
| 96 | +#include "postgres_fdw.h" |
| 97 | + |
| 98 | +static Oid serverid = InvalidOid; |
| 99 | +static UserMapping *user = NULL; |
| 100 | + |
| 101 | +static bool |
| 102 | +pgfdw_cancel_query(PGconn *conn) |
| 103 | +{ |
| 104 | + PGcancel *cancel; |
| 105 | + char errbuf[256]; |
| 106 | + PGresult *result = NULL; |
| 107 | + |
| 108 | + if ((cancel = PQgetCancel(conn))) |
| 109 | + { |
| 110 | + if (!PQcancel(cancel, errbuf, sizeof(errbuf))) |
| 111 | + { |
| 112 | + ereport(WARNING, |
| 113 | + (errcode(ERRCODE_CONNECTION_FAILURE), |
| 114 | + errmsg("could not send cancel request: %s", |
| 115 | + errbuf))); |
| 116 | + PQfreeCancel(cancel); |
| 117 | + return false; |
| 118 | + } |
| 119 | + |
| 120 | + PQfreeCancel(cancel); |
| 121 | + } |
| 122 | + else |
| 123 | + elog(FATAL, "Can't get connection cancel descriptor"); |
| 124 | + |
| 125 | + PQconsumeInput(conn); |
| 126 | + PQclear(result); |
| 127 | + |
| 128 | + return true; |
| 129 | +} |
| 130 | + |
| 131 | +static void |
| 132 | +cancelQueryIfNeeded(PGconn *conn, const char *query) |
| 133 | +{ |
| 134 | + Assert(conn != NULL); |
| 135 | + Assert(query != NULL); |
| 136 | + |
| 137 | + if (PQtransactionStatus(conn) != PQTRANS_IDLE) |
| 138 | + { |
| 139 | + PGresult *res; |
| 140 | + |
| 141 | + printf("CONN status BEFORE EXEC: %d, txs: %d errmsg: %s\n", |
| 142 | + PQstatus(conn), |
| 143 | + PQtransactionStatus(conn), |
| 144 | + PQerrorMessage(conn)); |
| 145 | + |
| 146 | + res = PQgetResult(conn); |
| 147 | + |
| 148 | + if (PQresultStatus(res) == PGRES_FATAL_ERROR) |
| 149 | + Assert(pgfdw_cancel_query(conn)); |
| 150 | + else |
| 151 | + pgfdw_get_result(conn, query); |
| 152 | + } |
| 153 | + |
| 154 | +} |
| 155 | + |
| 156 | +/* |
| 157 | + * We need to send some DML queries for sync database schema to a plan execution |
| 158 | + * at a remote instance. |
| 159 | + */ |
| 160 | +static void |
| 161 | +HOOK_Utility_injection(PlannedStmt *pstmt, |
| 162 | + const char *queryString, |
| 163 | + ProcessUtilityContext context, |
| 164 | + ParamListInfo params, |
| 165 | + QueryEnvironment *queryEnv, |
| 166 | + DestReceiver *dest, |
| 167 | + char *completionTag) |
| 168 | +{ |
| 169 | + Node *parsetree = pstmt->utilityStmt; |
| 170 | + |
| 171 | + if (ExtensionIsActive() && |
| 172 | + pstmt->canSetTag && |
| 173 | + (context != PROCESS_UTILITY_SUBCOMMAND) |
| 174 | + ) |
| 175 | + { |
| 176 | + if (!user) |
| 177 | + { |
| 178 | + MemoryContext oldCxt = MemoryContextSwitchTo(TopMemoryContext); |
| 179 | + |
| 180 | + serverid = get_foreign_server_oid(remote_server_fdwname, true); |
| 181 | + Assert(OidIsValid(serverid)); |
| 182 | + |
| 183 | + user = GetUserMapping(GetUserId(), serverid); |
| 184 | + MemoryContextSwitchTo(oldCxt); |
| 185 | + } |
| 186 | + switch (nodeTag(parsetree)) |
| 187 | + { |
| 188 | + case T_CopyStmt: |
| 189 | + case T_CreateExtensionStmt: |
| 190 | + case T_ExplainStmt: |
| 191 | + case T_FetchStmt: |
| 192 | + case T_VacuumStmt: |
| 193 | + break; |
| 194 | + default: |
| 195 | + if (nodeTag(parsetree) == T_TransactionStmt) |
| 196 | + { |
| 197 | + TransactionStmt *stmt = (TransactionStmt *) parsetree; |
| 198 | + |
| 199 | + if ( |
| 200 | +// (stmt->kind != TRANS_STMT_ROLLBACK_TO) && |
| 201 | + (stmt->kind != TRANS_STMT_SAVEPOINT) |
| 202 | + ) |
| 203 | + break; |
| 204 | + } |
| 205 | + if (conn) |
| 206 | + cancelQueryIfNeeded(conn, queryString); |
| 207 | + conn = GetConnection(user, true); |
| 208 | + cancelQueryIfNeeded(conn, queryString); |
| 209 | + Assert(conn != NULL); |
| 210 | + |
| 211 | + Assert(PQsendQuery(conn, queryString)); |
| 212 | + break; |
| 213 | + }; |
| 214 | + } |
| 215 | + |
| 216 | + if (next_ProcessUtility_hook) |
| 217 | + (*next_ProcessUtility_hook) (pstmt, queryString, context, params, |
| 218 | + queryEnv, dest, completionTag); |
| 219 | + else |
| 220 | + standard_ProcessUtility(pstmt, queryString, |
| 221 | + context, params, queryEnv, |
| 222 | + dest, completionTag); |
| 223 | + if (conn) |
| 224 | + cancelQueryIfNeeded(conn, queryString); |
| 225 | +} |
| 226 | + |
| 227 | +static void |
| 228 | +HOOK_ExecStart_injection(QueryDesc *queryDesc, int eflags) |
| 229 | +{ |
| 230 | + Node *parsetree = queryDesc->plannedstmt->utilityStmt; |
| 231 | + |
| 232 | + if (prev_ExecutorStart) |
| 233 | + prev_ExecutorStart(queryDesc, eflags); |
| 234 | + else |
| 235 | + standard_ExecutorStart(queryDesc, eflags); |
| 236 | + |
| 237 | + /* |
| 238 | + * This not fully correct sign for prevent passing each subquery to |
| 239 | + * the remote instance. Only for demo. |
| 240 | + */ |
| 241 | + if (ExtensionIsActive() && |
| 242 | + queryDesc->plannedstmt->canSetTag && |
| 243 | + ((parsetree == NULL) || (nodeTag(parsetree) != T_CreatedbStmt)) && |
| 244 | + !(eflags & EXEC_FLAG_EXPLAIN_ONLY)) |
| 245 | + { |
| 246 | + Oid serverid; |
| 247 | + UserMapping *user; |
| 248 | + |
| 249 | + serverid = get_foreign_server_oid(remote_server_fdwname, true); |
| 250 | + Assert(OidIsValid(serverid)); |
| 251 | + |
| 252 | + user = GetUserMapping(GetUserId(), serverid); |
| 253 | + conn = GetConnection(user, true); |
| 254 | + cancelQueryIfNeeded(conn, queryDesc->sourceText); |
| 255 | + |
| 256 | + if (PQsendPlan(conn, serialize_plan(queryDesc, eflags)) == 0) |
| 257 | + pgfdw_report_error(ERROR, NULL, conn, false, queryDesc->sourceText); |
| 258 | + } |
| 259 | +} |
| 260 | + |
| 261 | +static void |
| 262 | +HOOK_ExecEnd_injection(QueryDesc *queryDesc) |
| 263 | +{ |
| 264 | + if (conn) |
| 265 | + cancelQueryIfNeeded(conn, queryDesc->sourceText); |
| 266 | + |
| 267 | + if (prev_ExecutorEnd) |
| 268 | + prev_ExecutorEnd(queryDesc); |
| 269 | + else |
| 270 | + standard_ExecutorEnd(queryDesc); |
| 271 | +} |
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